An interface card connector having a slotted seat and a locking mechanism having an end for connecting with the slotted seat. The memory is communicatively coupled to the processor. The fan assembly includes a fan and the motor housing. According to the invention, the inner wall of the capsule chamber is uneven in order to achieve a better emptying of the capsule than is obtained with a smooth inner surface. Specifically, each of the caster assemblies is connected to an associated side rail by a rivet nut that communicates only with the bottom surface of side rail. In order to improve the control, at least one further variable which represents the running stability of the engine, is included in the control of the control states andor the switch-over between the control states.